does anyone know where i can find pictures/videos and descriptions of autonomous vex robots( so far i’ve only seen the autonomous squarebot but has anyone built a more complex system using different types of sensors and programs?..):rolleyes: :rolleyes:
I have but for the most part the VEX just can’t handle it. I had a ultrasonic sensor programmed to take a full 180 degree sweep at 15 degree increments. It then sorted the readings from lowest to highest. Using the sorted readings it then re-read the nearest, and therefore the most important, points. It adjusted its drive according to which readings were the closest. If all of them were to close it changed to a ultrasonic sensor in the back and basically reversed its orientation.
I haven’t reached the point that I can say that the Vex microcontroler cannot handle autonomous. I built 3 square bot bugs, the final one using the ultrasonic rangefinder to very effectively avoid collision. I think that programming more advanced behaviors is tricky using EasyC but I bet someone could do it. I am using C and will post my code when I have something worth reading. A few people on the web have published ideas on how to program robot behaviors using subsumption based on Rodney Brooks’ work and its derivatives. I have some light sensors coming from ebay this week and I will soon add a heat-sensor so that my bugs have a purpose other than “drive forward until you hit something.” Right now I am working on a better base for autonmous development: a 6WD sojourner rover type using a rocker-bogey suspension – at least as best as I can make it.
My goal is to build a rover that can scan for people and drive toward them then shoot ping-pong balls at them. It will have some basic collision avoidance behavior as well. I haven’t used the remote since my first squarebot build and don’t plan to, and I say that with no snobbery but merely to highlight where my interests are. From what I have read I think that the vex microcontrollers are capable of doing what I need, just maybe a little slow so my rover, like the mars rover, may have to stop and take its bearings now and then.
If the vex controller cannot handle the processing I need in the future I plan to offload it to a ppc or an OOPIC like the jvex project does. I like the structure parts very much though and I plan to stick to Vex for that reason.
You can build low cost autonomous robots using a Parallax Stamp BS2/BSX to control the Vex servos and motors. The Parallax BOE BOT and SUMO Bot robot application software written in PBASIC can be used with Vex models as long as similar sensors are used (SONAR PING and Sharp IR Rangers).
The idea behind controlling these robots is to use a simple FInite State Machine (FSM) to model the behaviors such as Moth, Cricket, Follow, Avoid, etc., using Rodney Brooks Subsumpture and the Brattenberg behavior models for controlling robots.
See all the free Parallax STAMP applications that you can download and run as is or convert to Vex PIC18 C for the Vex Controller in order to get your autonomous robot or SUMO robot working quickly. This is what I used to get my fully autonomous robots working. The Parallax site is at www.parallaxinc.com .
I don’t see why you couldn’t build autonomous robots with Vex. Vex has a similar PIC controller and 16 io ports + serial. If you’re not into electronics vex is much easier to use. There are many different controllers out there and any serious interfacing to them requires some knowledge of electronics. Vex is plug and go.
Easy C is a tad limited but it is probably the most easy to use programming IDE I’ve used. Even if you switch over the MPlab there are examples of code to follow. There are only so many API commands after all.
I have used the square bot chassis and some code to have the bot wander around the room. It changes direction when it detects collisions and uses the ultrasonic sensor to avoid other items.
Vex is capable enough to make any “bug” type bot.
bill
My Hero 2007 Robot is currently controlled via Vex RC remote control, but I am in the process of upgrading it with a Parallax Servo Controller for autonomous operation. It currently uses 4 Vex motors for 4WD drive and 1 Vex motor to pan the robot’s head an owl like 0-180 Degrees or to rotate it continuously for maximum sensor coverage for obstacle avoidance and navigation around the house. Currently it can dance and move about very fast under Vex RC remote control.
You can for yourself the progress I have made so far with if you check out photos of my Hero 2007 Robot using the following link:
On http://hobbyvex.org I have instructions on using the easyC API without using the GUI if the GUI is what’s getting in the way.
I have built a PalmVex robot that uses the easyC API for various purposes such as roving with sonar collision avoidance, table edge detection, measure distance traveled, spiral, etc. I haven’t modeled that robot in MLCAD yet so I don’t have building instructions to share. I plan to have that soon though. I’ll post some code with the building instructions.
I agree with a previous post. There is no reason to avoid building autonomous robots even if you only have a Vex starter kit.